Heretofore, this type of mounting device has been designed such that the cage embraces the hole in the plate from the inside. In this type of mounting device, the cage holds the nut on one side of the plate and retaining clips extend through the hole in the plate to the other side of the plate. In many applications, it is necessary to have at one's disposal either side of the plate as a smooth bearing surface. In such applications the clips extending through the hole in the plate are inconvenient. Moreover, in the event the cage rises laterally only slightly above the nut and the plate is made from a relatively soft material, e.g. aluminum, the nut together with the cage may bend through when the bolt is screwed firmly up to the bearing surface.